Generally, an endoscope is a medical device for insertion into a body passageway or cavity that enables an operator, positioned at a remote external location, to view and/or perform certain surgical procedures at a site internal to the patient's body. As is known, endoscopes may be either rigid or flexible, the later type providing either active or passive deflection of at least a portion thereof to facilitate reaching the internal site of interest. In general, a flexible endoscope includes a long flexible tubular member equipped with, for example, a miniature viewing device, an illumination device, and/or one or more working channels. The endoscope has a proximal end that remains external to the patient and a distal end having an endoscope tip for insertion into a body cavity of the patient.
Passive flexible endoscopes simply allow for the tubular member to deflect as it is inserted into various portions of the body (typically following the pathway of an elongated organ or cavity). Active flexible endoscopes on the other hand, allow the user to manipulate controls (typically at the proximal end of the endoscope) to cause at least a portion of the endoscope (typically the distal end) to deflect or flex in one or more directions. It is these flexible endoscopes with which the present invention is most concerned.
In certain known devices, the tubular member comprises a synthetic resin, such as polyurethane resin or ethylene tetrafluoride resin. A problem exists with the soft tubular members in that the soft material is susceptible to damage under normal operating conditions. For example, when resin is exposed at the distal end portion of the insertion section, and a laser probe is passed through one of the channels, the laser beam energy radiated from the distal end of the insertion section may burn the distal end of the tube either directly or indirectly by reflections of the beam energy from an irradiated region of a subject's body. This can result in a loss of structural integrity at the distal end tip of the endoscope.
In prior art devices, such as U.S. Pat. No. 4,788,967 to Ueda, the insertion section of an endoscope has a plurality of insertion channels extending in the axial direction of the flexible tube. A rigid member is attached to the distal end of the tube. The rigid member has through holes communicating with the channels, respectively. However, designs incorporating such rigid members are only useful where the rigid member replaces a distal end portion of the flexible endoscope tube in order to communicate with the various channels. This may lead to manufacturing difficulties including the step of modifying the distal end portion to accept the rigid member, as well as the addition of a bulky rigid member. This results in an unnecessarily heavy ended insertion tube.
U.S. Pat. No. 5,085,659 to Rydell relates to a biopsy instrument comprises an elongated flexible tube having a sharpened metal sleeve affixed to its distal end. The sleeve may be connected to the tube using a ceramic plug. However, this design creates a metallic edge outside of the flexible tube channel, thus does not protect the inner surface of the working channel from normal wear and tear. Moreover, the ceramic plug occludes the biopsy channel limiting a surgeon's ability to place tools therein.
U.S. Pat. No. 4,872,458 to Kanehira et al. relates to a thermotherapy apparatus used for performing a thermotherapy for a diseased part of a tumor such as a cancer of a living body. A heating portion is arranged in a distal end portion at the body cavity side of a probe which can be inserted in the body cavity through an endoscope or the like or a distal end portion at the body cavity side of an insertion portion of the endoscope. The heating portion has a far-infrared radiation ceramic member, and a heater for heating the far-infrared radiation ceramic member. However, this design does not protect the interior portion of a working channel from wear and tear.
What is desired, therefore, is a durable working channel in a flexible endoscope the use of which does not result in a loss of deflection at the distal end tip of the endoscope, which does not break down easily under normal wear and tear conditions, which has high resilience, and which does not fatigue and permanently deform, thereby shortening the life of the endoscope.